Except for wildfire smoke, Garfield County recorded another good air quality year in 2020 | AspenTimes.com

Except for wildfire smoke, Garfield County recorded another good air quality year in 2020

Smoke hangs low in Glenwood Canyon from the Grizzly Creek Fire in August 2020.
File photo

While wildfire smoke made for several moderate to unhealthy air quality days for sensitive groups in Garfield County in 2020 — a phenomenon that’s continuing this year with smoke filtering in from out-of-state fires — the county overall registered good air quality last year.

And, with a continued decline in readings for volatile organic compounds (VOCs) that has come with the downturn in natural gas activity, the county is scaling back its monitoring for that particular pollutant, Garfield County Environmental Health Specialist Ted White reported to county commissioners at their Aug. 16 meeting.

“In 2020, we did have a spike in ozone days that put us over the threshold for the ambient air quality standard,” White said. “But overall, Garfield County air quality was below that range and in a good place.”

The county’s ambient air monitoring program found that most VOCs are declining, and there were no national ambient air quality standards (NAAQS) violations for ozone or particulate matter reported in 2020.

Garfield County’s air quality monitoring program takes in readings at five sites, including Parachute, Battlement Mesa, Rifle, Carbondale and Bell Ranch, which is south of Silt.

The county’s Environmental Health web page provides real-time data from the Rifle, Carbondale and Battlement Mesa sites.

“The Rifle site provides monitoring of ozone and PM2.5 (particulate matter), as well as a live feed camera,” White explained. “We monitor for ozone at the Carbondale, Rifle and Battlement Mesa sites, and nitrogen dioxide at the Battlement Mesa site.

“Particulate matter is monitored at the Rifle and Battlement Mesa sites,” he said, adding that all air monitoring reports from previous years can be found online.

VOCs have been measured in Garfield County since 2008 when concerns about air quality grew around the boom in natural gas drilling. In the years since, monitoring has shown a diminishing trend in the presence of VOCs in the county’s air.

“While we’re still monitoring VOCs in Battlement Mesa, we’ve discontinued sampling in Carbondale,” White said. “We just weren’t seeing anything that really warranted continued monitoring there.”

The county program analyzes 90 different compounds, including 21 hazardous air pollutants such as propane, benzene, formaldehyde and ethane that contribute to ground-level ozone formation when exposed to sunlight.

An ozone violation occurs when a three-year average of the fourth highest daily maximum eight-hour average exceeds 70 parts per billion (PPB), White explained. While ozone levels in Carbondale and Battlement Mesa registered above the NAAQS standard in 2020, the three-year average is still below the threshold, he said.

VOC monitoring has been done via the county’s mobile monitor in Battlement Mesa, as well as through cannister sampling at the fixed Rifle, Parachute and Bell Ranch sites.

Overall, Garfield County experienced 335 days of good air quality over a 24-hour period in 2020 for particulate matter of 2.5 microns (PM2.5), with 26 moderate days, and four days considered unhealthy for sensitive groups, according to a report prepared by the county’s air quality monitoring consultants, Air Resource Specialists.

The county also measured 258 days of good air quality for eight-hour ozone, with 103 in the moderate category and five in the unhealthy for sensitive groups level.

Several days in August and into early September of 2020 were polluted by wildfire smoke from two major fires locally, the Pine Gulch Fire in the far western part of Garfield County, and the Grizzly Creek Fire in Glenwood Canyon. Smoke also filtered into western Colorado from several other fires burning across the West, as has been the case for much of this summer.

Even so, the county remained below the NAAQS violation threshold in 2020, according to the county’s annual air quality report.

The Air Quality Index (AQI) is the standardized system that state and local air pollution control programs, including Garfield County, use to notify the public about levels of air pollution. It provides six different levels of air quality: good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous.

The “moderate” level indicates that air quality is acceptable, but that some pollutants may pose a moderate risk for a very small number of people who are hyper-sensitive to ozone. The “unhealthy for sensitive groups” level indicates that members of sensitive groups may experience health effects due to air pollution.

Over the past five years, Garfield County recorded only one “unhealthy” day for all groups of people. That was in 2018 during the height of the Lake Christine Fire near Basalt.

White said the county is working to develop a wildfire smoke preparedness plan that would establish safe indoor shelters for high-risk groups of people during bad air quality days.

More detailed information on the program’s findings is available at Garfield-County.com/air-quality/documents.

Senior Reporter/Managing Editor John Stroud can be reached at 970-384-9160 or jstroud@postindependent.com.

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